Strange noise when accelerating

[DamienCBR]

Hi all,
I have been getting a funny tizzing noise around 2,800 rpm to 3,200 rpm when under load, this mainly happens in 3rd and 4th, rare in 2nd and almost never in 1st. I thought it was probably adding the new exhaust and i would need the much spoken about Tizz bracket.

So tonight Eliseman and i get under the car to have a look. There is what appears to be a tizz bracket in place, fine. The heat shield was moving around, rivets lost etc, fixed that, now nice and solid. There was also nothing obviously and everything seemed tight.

So we take her for a little spin. Eliseman drives and can replicate the sound, actually your can pretty much guarantee it and his conclusion, "maybe it is induction".

Possible.....

it only happens at these revs and when under a degree of load.

Any suggestions.

D

"FROM ELISEMAN"
................................and not when gaining speed very slowly rather than accelerating (if you know what I mean). Neither does it do it on the overrun as the revs drop back through the rev band where it normally occurs.

It only seems to happen on hard acceleration when the engine is breathing deeply.

The sound is similar to that which you get when sucking through a straw.

Air leak possibly or just turbulence in the induction system. What do you think ??

[rfoster]

Could also be the handbrake cables under the floor rattling - they tend to do that around 2,500 to 3,000 rpm - a metallic rattling sound. There's a bracket or foam that can alleviate this as well.

[noodleman]

Have you checked for any obvious induction leaks?

[DamienCBR]

noodleman said:

Have you checked for any obvious induction leaks?

There was nothing immediate but that was the next stage, take it all off and have a look to see if there were.

D

[wacattack]

Have you tried running the car with the rear undertray off? See of anything is vibrating against that?

[DamienCBR]

nothing touching the undertray. All induction has been checked and is fine.

I think it is going to be a new Flexi for zorst.
It has only happened since new zorst
Flexi was undone and moved to fit new zorst
Only makes noise when engine is under load, hence heavier load more move from flexi
Same rpm as described by other poster

Are we thinking the same as me?
D

[Grinnders]

According to sources that know about these things...

The vibration noise is also said can be caused by disintegrating flexi-pipe.

There's an inner and an outer pipe. If you change the exhaust it is quite common to accidentally break the inner pipe without any visible signs.

I'm guessing if it had really deteriorated some of those fragments could end up downstream in the cat etc. this could affect power I suspect....

just a thought